textproduct: Quad Cities

KEY MESSAGES

- High pressure will remain draped over the region through the start of the work week, bringing seasonal temperatures and mostly clear skies.

- A storm system will pass through the area Tuesday into Wednesday, bringing the chance for thunderstorms. A few storms may be strong to severe.

- Another stretch of quieter weather returns late in the week and into the weekend, with limited precipitation chances.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 127 AM CDT Mon Aug 17 2026

The stretch of heavy rainfall and severe storms has finally come to a close, as high pressure slides over the region today. We are geared to have quite the beautiful start to the work week. Aside from diurnal cumulus, mostly clear skies will be seen, with light northwesterly winds and temperatures around 80. Tonight, high pressure will be southeast of the area, with llvl winds shifting southwesterly. An increase in llvl moisture will result, with increasing mid-high clouds through the night. Dry conditions will remain through much if not all of the night, with temperatures in the low-mid 60s. The HRRR continues to bring in a decaying line of showers/storms, largely impacting our northern counties and drying up as it progresses through the area. Although, much of the short term model suite keeps us dry through tonight.

A shortwave trof will approach the area later on Tuesday, with weak bouts of energy passing out ahead of it. A 20-30 KT LLJ will also be in place overhead, increasing moisture throughout. This will create an environment favorable for showers and storms, which can be seen as early as late morning. Although, forcing isn't best until later in the day, especially as a cold front crashes through the area. Thus, any shower/storm activity should remain isolated to scattered until the afternoon/evening hours. As the cold front approaches Tuesday evening/night, we may have an environment favorable for some organized convection. Deep-layer shear will largely remain in the 30- 40 KT range with sufficient instability, which would favor mixed- mode convection that can grow upscale into a line of storms. The environment in place would favor the chance for a few strong to severe storms, with wind gusts being the main concern. Comparing to previous forecast runs, the severe threat does seem to be decreasing a little. This could be due to the aforementioned daytime showers/storms, which may limit afternoon destabilization ahead of the cold front, leading to a more conditional threat. This will be something to continue monitoring as more short term guidance comes in. SPC seems to have picked up on this trend, keeping much of the area under a Marginal Risk, level 1/5, and trimming the Slight Risk, level 2/5, to our far west.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 127 AM CDT Mon Aug 17 2026

Wednesday morning, we may continue to see residual showers/storms as the cold front fully exits the area. At this point, the severe threat will be quite limited. Thus, we are not expecting many impacts at that point. Post-frontal airmass will kick in Wednesday, with light northeasterly winds and decreasing cloud cover. The remainder of the work week seems to be quiet, with a slightly cooler airmass in place and much lower humidity. We will remain under weak northwesterly flow aloft, with a few weak impulses in the flow. Although, with low moisture and lacking return flow, we are not expecting much rain for the rest of the week. As was mentioned in the previous discussion, any precipitation will largely be in the form of isolated instability showers. A few global models indicate chances late Friday into Saturday morning, but confidence is low on this. Will stick with what the NBM initialized, introducing 15-30% PoPs Friday evening/night. Otherwise, a much needed stretch of mostly-dry weather will be seen, with comfortable humidity and temperatures largely in the upper 70s.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1153 AM CDT Mon Aug 17 2026

VFR conditions expected through much if not all the TAF cycle. Fair weather cumulus around 3kft will begin to dissipate around sunset, with winds also becoming light. With mostly clear skies and calm wind late tonight, some guidance is hinting at some MVFR fog potential particularly at BRL/DBQ prior to sunrise. Left out mention for now as probabilities remain under 20%. A storm system to track across the upper Midwest overnight, bringing a chance of scattered showers late in the period at CID/DBQ and have included PROB30 groups for this possibility.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.